1. Field
The present invention relates to a power-source control system including at least one information processing apparatus, a required-power calculation apparatus which calculates electric power to be supplied to the information processing apparatus, a power-source apparatus which supplies electric power calculated using the required-power calculation apparatus to the information processing apparatus, and a power-source control apparatus which controls the power-source apparatus, and a power-source control method.
2. Description of the Related Art
General power-source apparatuses which supply electric power to information processing apparatuses, such as personal computers and servers, are known (refer to Japanese Patent Laid-Open No. 5-91660 and Japanese Patent Laid-Open No. 7-264776).
Such a power-source apparatus should attain high efficiency of power conversion as well as significant power, multi output, output stability against load change, and miniaturization.
Note that the efficiency of power conversion is represented by a rate of input power to output power.
That is, the lower the efficiency of power conversion, the larger heat-generation quantity of the power-supply apparatus (heat quantity generated due to electric power which is not output).
Therefore, such a power-source apparatus should include a cooling structure, such as a cooling fan.
Accordingly, since electric power should be supplied to the cooling structure, electric power which is unnecessarily consumed increases.
On the other hand, the higher the efficiency of power conversion, the lower the power-generation quantity of the power-source apparatus.
Therefore, a cooling structure is not required for the power-source apparatus having the high efficiency of power conversion.
Therefore, unnecessary electric power is less consumed.
Accordingly, the power-source apparatuses preferably have high efficiency of power conversion.
Note that it is known that the efficiency of power conversion of such a power-source apparatus is generally changed in accordance with consumption current of information processing apparatus(es).
FIG. 11 is a diagram illustrating a relationship between efficiency of power conversion of a power-source apparatus and consumption current of an information processing apparatus.
In an example illustrated in FIG. 11, when a consumption current of the information processing apparatus is 10A, the highest efficiency of power conversion is attained (efficiency of power conversion of 90%).
As the consumption current of the information processing apparatus becomes larger than 10A, and as the consumption current of the information processing apparatus is reduced so as to be smaller than 10A, the efficiency of power conversion is lowered.
Specifically, when a consumption current of the information processing apparatus is 20A, the efficiency of power conversion is 75%.
When a consumption current of the information processing apparatus is 2A, the efficiency of power conversion is 60%.
That is, the efficiency of power conversion is low when the consumption current of the information processing apparatus is high (20A in the example illustrated in FIG. 11) and when the consumption current of the information processing apparatus is low (2A in the example illustrated in FIG. 11). Therefore, there is a demand for a method and system for attaining high efficiency of power conversion in these cases.
To meet such a demand, a power-source control system including two power-source apparatuses, i.e., a DC/DC converter and a series regulator, a detector which detects a consumption current of an information processing apparatus, and a switch unit which selects one of the two power-source apparatuses to be used in accordance with a detected consumption current has been proposed (refer to Japanese Patent Laid-Open No. 5-91660).
Note that the DC/DC converter is a power-source apparatus which attains high efficiency of power conversion when consumption current of an information processing apparatus is large.
On the other hand, the series regulator is a power-source apparatus which attains high efficiency of power conversion when the consumption current of the information processing apparatus is small.
That is, the switch unit selects the DC/DC converter as the power-source apparatus when the consumption current of the information processing apparatus is large.
On the other hand, when the consumption current of the information processing apparatus is small, the series regulator is selected as the power-source apparatus to be used.
By this, in the both cases where the consumption current of the information processing apparatus is large and small, the high efficiency of power conversion of the power-source apparatuses is maintained.